Gantry Positioning Device TCP Displacement Compensation
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Solution Overview
Problem
Existing gantry-type positioning devices cannot accurately monitor and compensate for displacements of the tool center point (TCP) parallel to the plane during vertical movement of the functional element, leading to positioning inaccuracies.
Innovation Solution
The implementation of a gantry-type positioning device with a Z-carriage supporting the functional element, allowing movement in a third direction, and a position-measuring device on the Y-carriage and functional element to detect displacements in the X and Y directions, utilizing 1Dplus scales and scanning heads to achieve precise position measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the functional element is moved vertically by a Z-carriage, then functionality in the third direction is improved, but displacements parallel to the base plane cannot be monitored
Solution Approach 1:
The patent implements a feedback mechanism where a further position-measuring device continuously monitors the position of the functional element relative to the Y-carriage. This feedback system detects displacements in all directions including those parallel to the base plane during vertical movement, enabling real-time compensation for tool center point deviations
Solution Approach 2:
The patent introduces a second cross member as an intermediary reference element that is dimensionally stable and not influenced by mechanical or thermal loads. This intermediary serves as a stable reference frame against which the position of the Y-carriage and functional element can be measured, enabling detection of deviations without being affected by the deformation of the load-bearing first cross member
2Strength
If the first cross member carries the Y-carriage, then mechanical support is improved, but thermal and mechanical influences cause dimensional instability
Solution Approach 1:
The patent segments the cross member functionality into two separate components: the first cross member that bears mechanical and thermal loads for structural support, and the second cross member that serves exclusively as a dimensionally stable reference frame for measurement. This segmentation allows each component to be optimized for its specific function without compromise
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enables accurate detection and compensation of displacements in all degrees of freedom, enhancing positioning precision and simplifying the construction by eliminating separate actuators for the second cross member, allowing for more compact and efficient dual-gantry systems.
Implementation Method 1
scales are used which, in addition to the actual measuring track in the measurement direction, also carry what is referred to as a 'straightness track,' from which such small deviations transverse to the measurement direction can be read
Implementation Method 2
By scanning the scale tracks, periodic signals are obtained in response to a relative movement between the scale and the scanning head. Hence, the extent of the displacement, and thus a position, can be determined by counting the periods and subdividing the individual periods (interpolation)
Implementation Method 3
A further position-measuring device is disposed on the Y-carriage and the functional element such that a position of the functional element relative to the Y-carriage is detectable by the further position-measuring device
Data Source
AI summary
A gantry-type positioning device includes first and second cross members. Two linear guides are disposed parallel to each other on a base and support the first and second cross members such that the cross members are movable in a first direction. A Y-carriage has a functional element and is supported on the first cross member such that the Y-carriage and the functional element are movable in a second direction. A position-measuring device is disposed on the second cross member and the Y-carriage such that a position of the Y-carriage relative to the second cross member is detectable. A Z-carriage supports the functional element such that the functional element is movable relative to the Y-carriage in a third direction. A further position-measuring device is disposed on the Y-carriage and the functional element such that a position of the functional element relative to the Y-carriage is detectable.